Apparatus for establishing a priority call in a fixed wireless access communication system

ABSTRACT

Apparatus, and an associated method, for a fixed wireless access communication system, by which to initiate a call to an emergency dispatch center, or other priority call to a priority location. When communication resources are initially unavailable to permit establishment of the call, normal call set-up procedures are emulated at a subscriber station from which the call is to be originated. Communication resources are reallocated in the communication system to permit the establishment of the call and the call is thereafter established.

TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates generally to a manner by which toinitiate establishment of a priority call, such as a call to requestemergency assistance in a FWA (fixed wireless access), or other,communication system. More particularly, the present invention relatesto apparatus, and an associated method, by which to effectuate thepriority call even when communication resources are not initiallyavailable to establish the call. The initial unavailability of thecommunication resources is not made known to the user initiating thecall as normal system operation is emulated at a subscriber station fromwhich the call originates. And, when the call is determined to be apriority call, the communication resources of the communication systemare reallocated to provide communication resources to permit theestablishment of the priority call.

BACKGROUND OF THE INVENTION

[0002] Telecommunications access systems provide for voice, data, andmultimedia transport and control between the central office (CO) of thetelecommunications service provider and the subscriber (customer)premises. Prior to the mid-1970s, the subscriber was provided phonelines (e.g., voice frequency (VF) pairs) directly from the Class 5switching equipment located in the central office of the telephonecompany. In the late 1970s, digital loop carrier (DLC) equipment wasadded to the telecommunications access architecture. The DLC equipmentprovided an analog phone interface, voice CODEC, digital datamultiplexing, transmission interface, and control and alarm remotelyfrom the central office to cabinets located within business andresidential locations for approximately 100 to 2000 phone lineinterfaces. This distributed access architecture greatly reduced linelengths to the subscriber and resulted in significant savings in bothwire installation and maintenance. The reduced line lengths alsoimproved communication performance on the line provided to thesubscriber.

[0003] By the late 1980s, the limitations of data modem connections overvoice frequency (VF) pairs were becoming obvious to both subscribers andtelecommunications service providers. ISDN (Integrated Services DigitalNetwork) was introduced to provide universal 128 kbps service in theaccess network. The subscriber interface is based on 64 kbpsdigitization of the VF pair for digital multiplexing into high speeddigital transmission streams (e.g., T1/T3 lines in North America, E1/E3lines in Europe). ISDN was a logical extension of the digital networkthat had evolved throughout the 1980s. The rollout of ISDN in Europe washighly successful. However, the rollout in the United States was notsuccessful, due in part to artificially high tariff costs which greatlyinhibited the acceptance of ISDN.

[0004] More recently, the explosion of the Internet and deregulation ofthe telecommunications industry have brought about a broadbandrevolution characterized by greatly increased demands for both voice anddata services and greatly reduced costs due to technological innovationand intense competition in the telecommunications marketplace. To meetthese demands, high speed DSL (digital subscriber line) modems and cablemodems have been developed and introduced. The DLC architecture wasextended to provide remote distributed deployment at the neighborhoodcabinet level using DSL access multiplexer (DSLAM) equipment. Theincreased data rates provided to the subscriber resulted in upgradeDLC/DSLAM transmission interfaces from T1/E1 interfaces (1.5/2.0 Mbps)to high speed DS3 and OC3 interfaces. In a similar fashion, the entiretelecommunications network backbone has undergone and is undergoingcontinuous upgrade to wideband optical transmission and switchingequipment.

[0005] Similarly, wireless access systems have been developed anddeployed to provide broadband access to both commercial and residentialsubscriber premises. Initially, the market for wireless access systemswas driven by rural radiotelephony deployed solely to meet the universalservice requirements imposed by government (i.e., the local telephonecompany is required to serve all subscribers regardless of the cost toinstall service). The cost of providing a wired connection to a smallpercentage of rural subscribers was high enough to justify thedevelopment and expense of small-capacity wireless local loop (WLL)systems.

[0006] Deregulation of the local telephone market in the United States(e.g., Telecommunications Act of 1996) and in other countries shiftedthe focus of fixed wireless access (FWA) systems deployment from ruralaccess to competitive local access in more urbanized areas. In addition,the age and inaccessibility of much of the older wired telephoneinfrastructure makes FWA systems a cost-effective alternative toinstalling new, wired infrastructure. Also, it is more economicallyfeasible to install FWA systems in developing countries where the marketpenetration is limited (i.e., the number and density of users who canafford to pay for services is limited to small percent of thepopulation) and the rollout of wired infrastructure cannot be performedprofitably. In either case, broad acceptance of FWA systems requiresthat the voice and data quality of FWA systems must meet or exceed theperformance of wired infrastructure.

[0007] Wireless access systems must address a number of uniqueoperational and technical issues including:

[0008] 1) Relatively high bit error rates (BER) compared to wire line oroptical systems; and

[0009] 2) Transparent operation with network protocols and protocol timeconstraints for the following protocols:

[0010] a) ATM;

[0011] b) Class 5 switch interfaces (domestic GR-303 and internationalV5.2);

[0012] c) TCP/IP with quality-of-service QoS for voice over IP (VOIP)(i.e., RTP) and other H.323 media services;

[0013] d) Distribution of synchronization of network time out to thesubscribers;

[0014] 3) Increased use of voice, video and/or media compression andconcentration of active traffic over the air interface to conservebandwidth;

[0015] 4) Switching and routing within the access system to distributesignals from the central office to multiple remote cell sites containingmultiple cell sectors and one or more frequencies of operation persector; and

[0016] 5) Remote support and debugging of the subscriber equipment,including remote software upgrade and provisioning.

[0017] Unlike physical optical or wire systems that operate at bit errorrates (BER) of 10⁻¹¹, wireless access systems have time varying channelsthat typically provide bit error rates of 10⁻³ to 10⁻⁶. The wirelessphysical (PHY) layer interface and the media access control (MAC) layerinterface must provide modulation, error correction and ARQ protocolthat can detect and, where required, correct or retransmit corrupteddata so that the interfaces at the network and at the subscriber siteoperate at wire line bit error rates.

[0018] The wide range of equipment and technology capable of providingeither wireline (i.e., cable, DSL, optical) broadband access or wirelessbroadband access has allowed service providers to match the needs of asubscriber with a suitable broadband access solution. However, in manyareas, the cost of cable modem or DSL service is high. Additionally,data rates may be slow or coverage incomplete due to line lengths. Inthese areas and in areas where the high cost of replacing old telephoneequipment or the low density of subscribers makes it economicallyunfeasible to introduce either DSL or cable modem broadband access,fixed wireless broadband systems offer a viable alternative. Fixedwireless broadband systems use a group of transceiver base stations tocover a region in the same manner as the base stations of a cellularphone system. The base stations of a fixed wireless broadband systemtransmit forward channel (i.e., downstream) signals in directed beams tofixed location antennas attached to the residences or offices ofsubscribers. The base stations also receive reverse channel (i.e.,upstream) signals transmitted by the broadband access equipment of thesubscriber.

[0019] Unfortunately, the diversity of broadband access technology hasresulted in a lack of standardization in the broadband access equipment.Cable modems and DSL routers are incompatible with each other and withfiber optic equipment. Different service providers locate broadbandaccess equipment in different locations on the subscriber premises.Often this equipment is located inside the office or residence of thesubscriber, which makes it inaccessible to maintenance workers unlessthe subscriber is present to admit the workers to the premises. The lackof standardization of broadband access equipment and the frequentinaccessibility of such equipment adds to the cost and complexity ofbroadband access.

[0020] Therefore, there is a need in the art for broadband accessequipment that can be readily and inexpensively deployed in the largedomestic and international markets that are not currently served bywired or wireless broadband access technology. Further, there is a needfor an apparatus to increase the communication capacity of thecommunication system.

[0021] Concentration techniques are utilized in construction of manymulti-user communication systems. Concentration techniques, generally,refer to selection of the number of users permitted to be part of thesystem to be greater, by some factor, than the actual capacity of thecommunication system. Statistical, or other, analysis is made of thelikely number of users of the communication system at any particulartime, and the system is constructed to support a number of users basedupon the expected number of users.

[0022] During times in which actual usage of the communication exceedsthe capacity of the system, additional users, beyond the system'scapacity, are prevented, or blocked, from access to the system.

[0023] When the communication system comprises a conventional wireline,telephonic communication system, the additional users are providedindication of their failure to access the system by alerting such userswith audible alerts. The audible alerts are audibly distinct from normaldial tones generated during normal telephonic operation.

[0024] In a fixed wireless access communication system, capacitylimitations are possible between both the network infrastructure of thesystem and a correspondent node forming a terminating or originatingstation as well as, additionally, the radio links extending between thenetwork infrastructure and the subscriber stations.

[0025] When, for instance, a user at the subscriber station needs toplace a priority call, such as a request for emergency assistance to anemergency dispatch center, access to the communication system tocommunicate with the emergency dispatch center is essential. A needtherefore exists to provide access to a communication system toestablish the priority call with the emergency dispatch center. It wouldalso be desirable to provide a manner by which to operate thecommunication system in which the user is not made aware of an initialblockage from access to the system if access shall subsequently begranted.

[0026] It is in light of this background information related to radiocommunication systems that the significant improvements of the presentinvention have evolved.

SUMMARY OF THE INVENTION

[0027] The present invention, accordingly, advantageously providesapparatus, and an associated method, by which to initiate establishmentof a priority call, such as a call to request emergency assistance, in aFWA (fixed wireless access), or other, communication system.

[0028] Through operation of an embodiment of the present invention, amanner is provided by which to effectuate the priority call even whenthe communication resources are not initially available to establish thecall.

[0029] When a call is initiated, the initial unavailability of thecommunication resources is not made known to the user initiating thecall as normal system operation is emulated at the subscriber station atwhich the call is originated. The communication resources of thecommunication system are reallocated, when the call is determined to bea priority call, to provide communication resources to permit theestablishment of the priority call.

[0030] In one aspect of the present invention, apparatus is provided fora subscriber station operable in a fixed wireless access communicationsystem. When a priority call is originated at the subscriber station,the user of the subscriber station takes the telephonic station locatedthereat off-hook. When the telephonic station is off-hook, a callestablishment message is generated and sent by way of a radio link tonetwork infrastructure of the fixed wireless access system. Theestablishment message is generated as a precurser to a request toestablish the call between the subscriber station and anothercommunication station. Detection is made at the network infrastructureof the call establishment message. Responsive thereto, determination ismade of the communication resource availability in the communicationsystem to establish an additional call, of indeterminate priority. Aresponse indicating whether communication resources are available in thecommunication system to establish the call of indeterminate priority isreturned to the subscriber station.

[0031] A response detector at the subscriber station is coupled toreceive indications of the response to the call establishment message.Indication of whether communication resources are available to establishthe call is detected thereat. If communication resources areunavailable, a call set-up emulator is operable to emulate at thesubscriber station normal call set-up operations. To the user of thesubscriber station at which the call is initiated, call set-upoperations appear to be normally progressing.

[0032] Dialing digits associated with the terminating station with whichthe call is to be established are entered at the subscriber station. Adialing digit signal is then sent to the network infrastructure.Determination is made at the network infrastructure of the priority tobe associated with the call which is to be established. If the call is apriority call, such as a call to an emergency dispatch center, e.g.,indicated by a pseudo-universal dialing code, such as 9-1-1, resourcereallocations are effectuated to permit the establishment of the call.Thereafter, the call is established.

[0033] In one implementation, apparatus is provided for a subscriberstation operable in the FWA system. A call set-up emulator is selectablyoperable to emulate normal call set-up operations at the subscriberstation even when communication resources are not initially available toestablish a call by the subscriber station. A dial-tone generatorgenerates a dial tone audibly detectable by the user of the subscriberstation in which the call is originated. Dialing digits associated withthe call originated at the subscriber station are also enterable inapparent normal fashion at the subscriber station. Upon subsequentreallocation of communication resources in the FWA communication system,the call establishment commences in normal manner.

[0034] In a further implementation, apparatus is provided for thenetwork infrastructure of the FWA system, such as at an access processoror base transceiver station of the system. A detector is coupled todetect a call establishment message transmitted to the networkinfrastructure. Responsive to receipt of the call establishment message,determinations are made of the availability of communication resourcesto establish a call in the communication system. A response is then sentto the originating subscriber station. Thereafter, indications of theidentity of the terminating station to which a call is to be establishedare D received at the network infrastructure. If the identify of theterminating station indicates that the call is a priority call,reallocation of communication resources is made, if necessary, to permitthe establishment of the call. If communication resources are nototherwise available, an ongoing communication session is terminated toprovide the communication resources to effectuate the call.

[0035] In these and another aspects, therefore, apparatus, and anassociated method, is provided for a multi-user FWA (fixed wirelessaccess) communication system in which a plurality of subscriber stationsare operable to communicate by way of radio links with networkinfrastructure to which a correspondent node is coupled. A call of aselected call-type is selectably originated at a selected subscriberstation. A call establishment message generator is coupled to receive anindication of initiation at the selected subscriber station oforigination of the call. The call establishment message generatorgenerates a call establishment message for communication to the networkinfrastructure to initiate call set-up procedures which precurse arequest to establish the call between the selected subscriber stationand the correspondent node. A response detector is coupled to receive anindication of a network-infrastructure generated to respond to the callestablishment message generated by the call establishment messagegenerator. The response detector detects whether the response to thecall establishment indicates communication resources to be available toestablish the call. A call set-up emulator is coupled to the responsedetector. The call set-up emulator is operable to emulate at theselected subscriber station normal call set-up operations thereat. Thenormal call set-up operations are emulated for a selected periodresponsive to detection by the response detector of unavailability ofthe communication resources to establish the priority call.

[0036] The present invention will be better understood when read inlight of the accompanying drawings which are described in the detaileddescription hereinbelow and in light of the claims appended hereto.

BRIEF DESCRIPTION OF THE DRAWINGS

[0037]FIG. 1 illustrates a functional block diagram of an exemplaryfixed wireless access (FWA) network in which an embodiment of thepresent invention is operable.

[0038]FIG. 2 illustrates an exemplary data frame, as defined by thefixed wireless access network in FIG. 1, according to an embodiment ofthe present invention;

[0039]FIG. 3 illustrates a functional block diagram of portions of thefixed wireless access communication system shown in FIG. 1.

[0040]FIG. 4 illustrates a message sequence diagram exemplary ofsignaling generated during operation of the communication system shownin FIGS. 1 and 3 pursuant to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0041] Referring first to FIG. 1, a communication system, showngenerally at 10, provides for communications with the subscriberstations, of which the subscriber station 12 is exemplary.Communications are effectuated with the subscriber station by way ofradio links formed upon an air interface 14. Data originated at anappropriately-positioned subscriber station can be communicated to acorrespondent node, 16 by way of a communication path by way of theradio links formed upon the air interface. Data originated at thecorrespondent node 16 can be communicated upon a communication pathformed between a correspondent node and a subscriber station. Two-waycommunication between the subscriber station and the correspondent nodeis thereby possible.

[0042] In the exemplary implementation, the communication system 10forms a fixed wireless access (FWA) system coupled to a networkbackbone, of which the combined path data network (PDN) andpublic-switched telephonic network (PSTN) 18 is representative in thefigure.

[0043] While the following description of operation of an embodiment ofthe present invention shall describe its operation with respect to theexemplary implementation of the communication system shown in thefigure, it should be understood that operation of an embodiment of thepresent invention is analogously also operable in other types ofcommunication systems which use concentration techniques or otherwiseare susceptible to access limitations.

[0044] The fixed wireless access system includes a plurality of basetransceiver stations of which the base transceiver/remote modem (BTS/RM)22 shown in the figure is exemplary. Each base transceiver stationdefines a cell. Here, the base transceiver station 22 defines a cell 24.The subscriber station 12 is here positioned at a location encompassedby the cell 24. A plurality of other subscriber stations are alsopositionable at locations encompassed by the cell 24. And, othersubscriber stations positioned in other cells defined by other basetransceiver stations typically form parts of a fixed wireless accesscommunication system.

[0045] Concentration techniques are used in system construction. That isto say, system construction permits a high ratio of subscriber stationsto base transceiver stations such that, if all of the subscriberstations simultaneously attempt to effectuate communication sessions,the communication capacity of the base transceiver stations would beexceeded. Through the use of concentration techniques, a statistical, orother, determination is made of an appropriate number of subscriberstations to be permitted to be associated with a particular basetransceiver station. Not all of the subscriber stations are likely toattempt to effectuate simultaneous communication sessions, therebypermitting the number of permitted subscriber stations to be increased.

[0046] While any of the a large variety of different types ofcommunications are effectuable, of significance to an embodiment of thepresent invention are telephonic communications originated at thesubscriber station. A telephonic station 26 is here shown to be locatedat the subscriber station 12.

[0047] Use of the terminology communications by the subscriber stationand by the telephonic station shall be used, at times, interchangeablybelow to indicate communications by the telephonic station with thecorrespondent node 16. And, while only a telephonic station 26 is shownto be positioned at the subscriber station, other types of communicationdevices such as computer stations and consumer-electronic devices, canalso be represented at the subscriber station.

[0048] An integrated access device (IAD) 28 is also shown to bepositioned at the subscriber station. The integrated access device (IAD)unit includes transceiver circuitry capable of communicating by way ofthe air interface with the base transceiver station 22. The telephonicstation 26 is coupled to the integrated access device 28 andcommunications are effectuated with the subscriber station by way of theintegrated access device.

[0049] The base transceiver station 22 forms a portion of the networkinfrastructure of the fixed wireless access system. Groups of basetransceiver stations are coupled to an access processor (AP) 32. And, inturn, the access process is coupled to the network 18. During operationof an embodiment of the present invention, communication resourcesrequired to establish a call between the telephonic station 26 and thecorrespondent node 16 are selectably provided. Communication resourcesboth at the air interface 14 and through the network 18 must beavailable to establish the call between the telephonic station 26 andthe correspondent node 16.

[0050]FIG. 2 illustrates portions of the communication system 10 toillustrate operation of an embodiment of the present invention.Operation of an embodiment of the present invention permits a user ofthe telephonic station 26 positioned at the subscriber station 12 tooriginate a call to an emergency dispatch center 34 at which thecorrespondent node 16 is located.

[0051] Elements shown in the figure are functional representations,portions of which are implemented, in exemplary implementation, asalgorithms executable at processing devices. Additionally, functionaloperation of the various elements, or portions thereof, can bedistributed at several locations or elements of the communicationsystem. Here, for instance, the transmit and receive circuitry portions36 and 38 are implemented at the integrated access device 28, at thetelephonic station 26, or at other portions of the subscriber stations.

[0052] When a call is placed to the emergency dispatch center, apseudo-universal dialing code, such as a 9-1-1 dialing code is enteredat the telephonic station of the subscriber station.

[0053] A user interface 42 is also positioned at the subscriber station.The user interface includes, for instance, an actuation key pad locatedon the telephonic station which permits user actuation thereof to enterdialing digits associated with a terminating station such as thecorrespondent node 16 at the emergency dispatch center 34. The userinterface is also representative of a hook switch associated with thetelephonic station upon which a telephonic handset is conventionallypositioned, to be removed therefrom when a call is to be initiated.

[0054] The user interface is coupled to apparatus 44 of an embodiment ofthe present invention. The apparatus 44 is formed of functional elementsimplemented, for instance, by algorithms executable by controlcircuitry.

[0055] Here, a call establishment message generator 46 is coupled to theuser interface to receive indications of off-hook indications indicatedthereat. An off-hook indication is indicated when a telephonic stationis taken off the hook switch when a user intends to initiate a call witha terminating station. The call establishment message generatorgenerates a call establishment message when the off-hook indication isprovided thereto. The call establishment message is provided to thetransmit circuitry 36 to be transmitted to the network infrastructure toinform the network infrastructure of the imminent request forestablishment of a call with a terminating station.

[0056] The network infrastructure, here formed of both the basetransceiver station 22 and access processor 32 is also shown to includeboth transmit circuitry and receive circuitry portions 52 and 54,respectively. The transmit and receive circuitry portions areimplemented, for example, at the base transceiver station 22.

[0057] The call establishment message transmitted by the subscriberstation to the network infrastructure is detected at the receivecircuitry 52. Apparatus of an embodiment of the present invention, herereferenced at 56 is coupled to the receive and transmit circuitry 52 and54. Elements forming the apparatus 56 are also functionally representedand can be implemented in any of various manners, including byalgorithms executable by control circuitry.

[0058] And, the elements forming the apparatus 56 can be distributed atdifferent locations of the network infrastructure or coupled thereto.

[0059] When a call establishment message is received at the receivecircuitry, detection is made of its reception by a call establishmentmessage detector 58. The call establishment message detector is coupledto a communication resource availability determiner 62. Thecommunication resource availability determiner It is operable at leastresponsive to detection of reception of the call establishment messageat the network infrastructure. The communication resource availabilitydeterminer is operable to determine the availability of communicationresources, both in the network 18 and upon the air interface 14, ofcommunication resources to establish a call of indeterminate priority.

[0060] Determinations are made, for instance, responsive to indicationsof other ongoing communication sessions with other subscriber stationsas well as ongoing communication sessions making use of the network 18.

[0061] Determinations made by the determiner 62 are provided to aresponse generator 64. The response generator generates a responsesignal which is provide to the transmit circuitry 54. The responsesignal is transmitted by way of the air interface 14 to the subscriberstation 12. The response serves to acknowledge reception at the networkinfrastructure of the call establishment message and also to provide anindication to the subscriber station of the availability ofcommunication resources to establish a call originated at the subscriberstation.

[0062] When the response is received at the receive circuitry 38 of thesubscriber station, a response detector 68 detects reception at thesubscriber station of the response. If the response indicates thatcommunication resources are unavailable to establish a call, originatedat the subscriber station, an indication is provided to a call set-upemulator 72. The call set-up emulator is operable to emulate normaloperation of call set-up procedures even though the response indicatesthe communication resources to be unavailable to establish the call. Thecall set-up emulator includes, for instance, a dial tone generator whichgenerates a conventional telephonic dial tone audibly detectable by auser of the telephonic station. Here, the oscillator 74 isrepresentative of an oscillating signal used in the generation of a dialtone. The emulator is also coupled to the user interface 42 to receiveindications of dialing digits or other actuator inputs input by way ofthe user interface. For instance when dialing digits are entered, thegenerated dial tone is terminated and appropriate audibly-detectabletones are generated responsive to the entry of the dialing digits orother input actuations.

[0063] Indications of the entered dialing digits are also provided to adialing digit signal generator 76. The dialing signal generatorgenerates a dialing digit signal which is provided to the transmitcircuitry 36 to be transmitted to the network infrastructure.

[0064] When the dialing digit signal is received at the receivecircuitry, detection of the signal is made by a dialing digit indicationdetector 82. The detector 82 detects the values of the dialing digits.Detection is at least made as to whether the values of the dialingdigits are those corresponding to the emergency dispatch center, orother priority location. When detection is made of dialing digitscorresponding to the emergency dispatch center, or other prioritylocation, an indication of such is given to a resource reallocator 84.The resource reallocator is operable to reallocate the allocation ofcommunication resources in the communication system to permit theestablishment of the call between the subscriber station and theemergency dispatch center. Resource reallocation caused to beeffectuated by the resource reallocator includes, for instance,termination of ongoing communication sessions to make available thecommunication resources to permit the call to the emergency dispatchcenter, or other priority location, to be established. Selection ofwhich of the ongoing communication session, or sessions, to beterminated is made, for instance, upon random selection, or based uponsubscription service levels to which the different subscriber stationshave subscribed.

[0065] Thereby, a call is able to be established between the subscriberstation and the emergency dispatch center, even when the communicationresources are not initially available to permit the establishment of thecall. And, through the use of the call set-up emulator at the subscriberstation, the originator of the call is not made aware of the initialunavailability of the communication resources.

[0066]FIG. 3 again shows portions of the fixed wireless network, hereshown at 300 of an embodiment of the present invention. The Fixedwireless network, is here show to include a subscriber integrated accessdevice (SIAD) 304 located at a subscriber premises. The SIAD 304includes radio circuitry 306 capable of transceiving radio signals. Witha transceiver base station 308.

[0067] The radio circuitry 306 of the SIAD 304 is here capable ofgenerating both voice and data packets, here represented by the blocks312 and 314. The voice packets are representative of voice packetsgenerated during operation of a telephony handset which is operable inconvention manner but connected to the radio circuitry of the SIAD.

[0068] The transceiver base station is coupled to an access processorshelf 322 which here functionally is shown to include a table 324 atwhich active call information is stored, and a resource allocator 326which allocates communication resources in the fixed wireless network.

[0069] The access processor communicates traffic and signalinginformation by way of the element 328 on the lines 332 with a networkinterface 334.

[0070] The network interface 334 is coupled to the PSTN/IP network 336.

[0071] The network 336 is, in tern, connected to a communicationstation, here located at an emergency dispatch center 338.

[0072] A telephony handset located at the SIAD 304 can be used, forinstance, to phone an emergency request for emergency assistance topersonnel at the emergency dispatch center. The call, when established,permits a call originator who places the call to request emergencyassistance.

[0073] Due to the potentially emergency nature of the call, it isessential that the call be established. Due to the use of concentrationtechniques in system construction, there is a possibility that systemcapacity would not permit establishment of the call, and the request foremergency assistance at the emergency dispatch center would not becompleted.

[0074] During operation of an embodiment of the present invention, amanner is provided by which to better assure that the call isestablished.

[0075]FIG. 4 illustrates a message sequence diagram, shown generally at400, representative of operation of a fixed wireless network shown inFIG. 3. Signaling is initiated at the SIAD 304 when a telephony handsetis taken off-hook. As soon as the telephony handset is taken off-hook, acall establishment message is generated, indicated by the segment 404,and sent to the access processor 322. A determination is made as towhether resources are available to establish a call. In the exemplaryscenario, resources are not available to establish a call, and anindication of the unavailability of the resources, indicated by thesegment 406, is returned to the SIAD.

[0076] Upon receipt of the indication of the unavailability of theresources, normal call set-up procedures are emulated, indicated by theblock 408. emulation procedures include, for instance, generation of adial tone which is local to the SIAD but otherwise appearing to benormal operation of the telephony handset to a user thereof. The user,upon detecting the dial tone, dials, or otherwise enters, digitsassociated with the emergency dispatch center, such as the emergencydigits 9-1-1 forming a pseudo universal emergency number in the UnitedStates. The entered digits of the dialing code are captured, indicatedat the block 410, and a digit message is generated and transmitted bythe segment 412 to the access processor 322.

[0077] At the access processor a determination is made as to whether thevalues of the digits contain in the digit message are associated withthe emergency dispatch center or are otherwise associated with thepriority call. If not, a terminate call message indicated by the segment414 is returned to the SIAD. A terminate call message is identified atthe telephony handset at the SIAD as a fast busy signal.

[0078] If, conversely, the digit message is of values corresponding toan emergency dispatch center, or is otherwise representative of apriority call, a decision is made to permit the establishment of thecall. To free resources to permit the establishment of the call, anonpriority call is terminated, indicated by the block 416. A nonpriority call is terminated, such as by randomly terminating an activecall selected from the table 324, (shown in FIG. 3). A priority mightalso be associated with the act of calls, and a lowest-priority act ofcall is first-terminated. Or, a random termination of a lowest-prioritycall is performed. Thereby, resources are made available to establishthe call between the telephony handset and the emergency dispatchcenter. Thereafter, and as indicated by the segment 418, a message issent to the PSTN to cause a call to be established therethrough. Normalcall operations, indicated by the block 422 is thereafter effectuated atthe 911, or other priority call, continues until one side, or the other,of the communication sessions goes on-hook.

[0079] The previous descriptions are of preferred examples forimplementing the invention, and the scope of the invention should notnecessarily be limited by this description. The scope of the presentinvention is defined by the following claims.

What is claimed is:
 1. In a multi-user FWA (fixed wireless access)communication system in which a plurality of subscriber stations areoperable to communicate by way of radio links with networkinfrastructure to which a correspondent node is coupled, an improvementof apparatus for a selected subscriber station of the plurality ofsubscriber stations at which a call of selected call-type is selectablyoriginated, said apparatus comprising: a call establishment messagegenerator coupled to receive an indication of initiation at the selectedsubscriber station of origination of the call, said call establishmentmessage generator for generating a call establishment message forcommunication to the network infrastructure to initiate call set-upprocedures precursing a request to establish the call between theselected subscriber station and the correspondent node; a responsedetector coupled to receive an indication of a network-infrastructuregenerated response to the call establishment message generated by saidcall establishment message generator, said response detector fordetecting whether the response to the call establishment messageindicates communication resources to be available to establish the call;and a call set-up emulator coupled to said response detector, said callset-up emulator operable to emulate at the selected subscriber stationnormal call set-up operations thereat at least for a selected periodresponsive to detection by said response detector of unavailability ofthe communication resources to establish the priority call.
 2. Theapparatus of claim 1 wherein said call set-up emulator comprises adial-tone generator, said dial-tone generator for generating an audiodial-tone at the selected subscriber station responsive to detection bysaid response detector of the unavailability of the communicationresources.
 3. The apparatus of claim 2 wherein said subscriber stationcomprises a telephonic station having an actuation keypad actuatable bya user to enter dialing digits associated with the correspondent nodeand wherein generation of the audio dial-tone by said dial-tonegenerator is terminated upon commencement of entry of the dialingdigits.
 4. The apparatus of claim 3 further comprising a dialing-digitsignal generator coupled to receive indications of entry of the dialingdigits at the actuation keypad said dialing-digit signal generator forgenerating a dialing-digit indication signal for communication to thenetwork infrastructure pursuant to the request to establish the callbetween the subscriber station and the correspondent node.
 5. Theapparatus of claim 1 wherein the correspondent node comprises anassistance center having a dialing code formed of dialing digitsassociated with the assistance center, wherein the call of the selectedcall-type comprises a priority call, and wherein the dialing-digitsignal generated by said dialing-digit signal generator is of valuescorresponding to the dialing code associated with the assistance centerwhen the user actuates the actuation keypad to cause entry of thedialing digits forming the dialing code associated with the assistancecenter.
 6. The apparatus of claim wherein the assistance centercomprises an emergency dispatch center having a pseudo-universal dialingcode associated therewith, wherein the priority call comprises anemergency call, and wherein the dialing-digit signal generated by saiddialing-digit signal generator is of values corresponding to thepseudo-universal dialing code associated with the emergency dispatchcenter when the user actuates the actuation keypad to cause entry of thedialing digits forming the pseudo-universal dialing code.
 7. In themulti-user FWA communication system of claim 1, a further improvement ofapparatus for the network infrastructure, said apparatus comprising; acall establishment message detector coupled to receive indications ofreceipt at the network infrastructure of the call establishment message;and a response generator coupled to said call establishment messagedetector, said response generator for generating the response to thecall establishment message.
 8. The apparatus of claim 7 furthercomprising a communication resource availability determiner operableresponsive to detection of the call establishment message by said callestablishment message detector, said communication resource availabilitydeterminer for determining whether communication resources are availableto establish the call.
 9. The apparatus of claim 8 wherein the networkinfrastructure is coupled to the correspondent node by way of a networkbackbone, and wherein said communication resource availabilitydeterminer determines both whether communication resources are availableupon the network backbone to establish the call and whethercommunication resources are available upon the radio links to establishthe call.
 10. The apparatus of claim 8 wherein the subscriber stationfurther sends a dialing digit indication signal to the networkinfrastructure and wherein said apparatus for the network infrastructurefurther comprises a dialing digit indication detector coupled to receiveindications of receipt at the network infrastructure of the dialingdigit indication signal.
 11. The apparatus for the networkinfrastructure of claim 10 further comprising a resource reallocatorcoupled to said dialing digit indication detector and to said resourceavailability determiner, said resource reallocator selectably operableto reallocate communication resources in the multi-user FWAcommunication system responsive to selected values contained in thedialing digit indication signal detected by said dialing digitindication detector.
 12. The apparatus of claim 11 wherein thecorrespondent node comprises an emergency dispatch center having apseudo-universal dialing code associated therewith, wherein the dialingdigit indication signal to which said dialing digit indication detectoris coupled to receive indications thereof is of values corresponding tothe pseudo-universal dialing code and wherein said resource reallocatorreallocates the communication resources to provide communicationresources to establish a call between the subscriber station and theemergency dispatch center.
 13. The apparatus of claim 12 wherein thecommunication resources of the FWA communication system are utilizedpursuant to a plurality of communication resources with a plurality ofsubscriber stations and wherein reallocation made by said resourcereallocator include termination of selected communication resources,thereby to reallocate resources to establish the call between thesubscriber station and the emergency dispatch center.
 14. The apparatusof claim 13 wherein the communication sessions have priority levelsassociated therewith and wherein selection of termination selectedcommunication sessions is made responsive to the priority levelsassociated with the communication sessions.